Olfactives

Olfactives, or odorants, are volatile chemical compounds that stimulate the sense of smell. When inhaled, they dissolve in the mucus of the olfactory epithelium and bind to odorant receptors on olfactory neurons, generating neural signals that the brain interprets as odors.

Olfaction relies on combinatorial receptor coding: each odorant may activate multiple receptor types, and each receptor can respond to several odorants. The perceived smell depends on molecular properties such as volatility, molecular size, functional groups, and shape, as well as concentration and context, including the presence of other odorants.

Olfactives come from natural sources, such as essential oils and aroma compounds derived from plants or animals, and from synthetic chemistry, where many odorants are produced for flavors, fragrances, and consumer products. They can be used individually or in blends; enantiomeric composition can affect odor notes and intensity.

Applications include flavors and fragrances, cosmetics, and household products. Regulatory oversight varies by jurisdiction and typically addresses safety, labeling, and allergenic potential. In many regions, odorants used in consumer products must pass safety assessments and be listed or restricted by bodies such as IFRA or equivalent cosmetic/regulatory agencies.

In research and industry, olfactives are identified and analyzed using techniques such as gas chromatography–olfactometry, where human assessors sniff the GC effluent to correlate chemical peaks with perceived odor. This helps determine odor activity values and odor thresholds for complex mixtures.